In order to realize uplink frequency domain scheduling, a User Equipment (UE, User Equipment) not only transmits a Demodulation Reference Signal (DM RS, Demodulation Reference Signal) on currently used bandwidths, but also needs to transmit a Sounding Reference Signal (SRS, Sounding Reference Signal) to a base station within a wider bandwidth, such that the base station acquires channel states on the respective bandwidths of the UE, and schedules proper time-frequency resources for the UE. To acquire the channel states on the entire bandwidth of a UE, the entire bandwidth usually needs to be divided into multiple frequency bands, and the UE transmits SRS in different frequency bands at different moments.
A UE transmits SRS in different frequency bands at different moments, hence different UEs may transmit SRS in a same frequency band at a same moment, in which case the different UEs may interfere with each other. In order to avoid the interference between UEs, a base station usually configures different orthogonal codes for the respective UEs in a same cell. Thus due to the orthogonality of the codes, even if the respective UEs transmit SRS in a same frequency band at a same moment, they would not interfere with each other.
However, such method can only guaranty that the codes used by the respective UEs in the same cell satisfy the orthogonality, while the codes used by UEs of different cells do not satisfy the orthogonality. As such, one UE transmitting SRS in a frequency band may interfere with the SRS received in the same frequency band by a base station of an adjacent cell. If the UE is close to the base station of the adjacent cell, then the produced interference may be a strong one, which will seriously affect the reception of SRS by the base station of the adjacent cell.
In a multi-antenna system, a UE may transmit signals from multiple antennas (or antenna ports), deteriorating the above-described situation. This is because that, in the related art, in order for a base station to simultaneously obtain the channel states of all the antennas of a same UE in a same frequency band, each antenna of the UE transmits SRS in the same frequency band at a same moment. If a UE is close to a base station of an adjacent cell, the SRS transmitted by all the antennas of the UE will become strong interference to the SRS received by the base station of the adjacent cell in the same frequency band, since the interference with the adjacent cell increases with the increasing of the number of antennas as compared with the situation of a single antenna, which will seriously affect accuracy of detection for SRS transmitted by UE of the base station of the adjacent cell.